Nucleotides & DNA/RNA structure and function

Question 1

What are biomacromolecules (7)

Answer 1

1. Biologically important molecules
2. Often large (macro) molecules - built up from smaller molecules
3. carbohydrates
4. lipids
5. proteins
6. nucleic acids
7. Often drug targets

Question 2

What are nucleic acids (2)

Answer 2

1. Deoxyribonucleic acid (DNA) - possesses genetic code
2. Ribonucleic acid (RNA) - processes information carried in DNA

Question 3

What are nucleotides (4)

Answer 3

1. building blocks of nucleic acid
2. 5-carbon sugar (pentose)
3. phosphate(s)
4. nitrogen-containing base.

Question 4

What are nucleosides

Answer 4

the sugar (pentose) and base

Question 5

What is the nucleoside structure (3)

Answer 5

1. carbon 5 of sugar attaches to phosphate
2. the base attaches to carbon 1.
3. the only structure that changes is the nitrogen base.

Question 6

How does oxygen affect the sugar of nucleic acids

Answer 6

deoxy = without oxygen on carbon 2

Question 7

What are heterocyclic bases (3)

Answer 7

1. heterocyclic because its got carbon as well as nitrogen.
2. Bicyclic - two systems used together (e.g. purine)
3. basic due to low electrons on nitrogen (purine)

Question 8

What are the common nucleic acid bases (5)

Answer 8

1. adenine - based on purine, amino
2. guanine - based on purine
3. cytosine - based on pyrimidine
4. thymine - based on pyrimidine
5. uracil - 2 cyclic ketones

Question 9

What is the nucleoside nomenclature (2)

Answer 9

1. when ribose is added to Guanine name changes to guanosine.
   adenine → adenosine, Uracil → uridine, etc…
2. When deoxyribose is added to guanine it becomes deoxyguanosine.
   adenine → deoxyadenosine, etc…

Question 10

What is the nucleoside function (5)

Answer 10

1. Building blocks of nucleic acids
2. Driving force for a number of chemical reactions – ATP, GTP
3. Used in glycogen and complex carbohydrate biosynthesis
4. Used in complex lipid synthesis
5. Intracellular signalling molecules
6. Form parts of coenzymes (molecules that work with enzymes to help them with metabolic processes) – NAD, FAD, CoA

Question 11

What is the primary structure of DNA (4)

Answer 11

1. Base on carbon 1
2. no oxygen on carbon 2
3. O on carbon 3 connects to the phosphate group of previous DNA
4. Carbon 5 connects to phosphate group on next DNA

Question 12

What does the phosphodiester on DNA and RNA do

Answer 12

makes it acidic

Question 13

What does the 5’ and 3’ end show on nucleic acids

Answer 13

the position of the carbon on the sugar

Question 14

How are bases paired in DNA (4)

Answer 14

1. A and T (adenine and thymine)
2. G and C (guanine and cytosine)
3. Complementary strands
4. Double helix - Watson-Crick model

Question 15

How does the standard Watson-Crick base pairing work (2)

Answer 15

1. G-C = three hydrogen bonds between bases
2. A-T = Two hydrogen bonds between bases (less energy to separate)

Question 16

How are nucleic acids targets for drugs

Answer 16

the major groove is where drugs can be inserted.

Question 17

What is the RNA structure (5)

Answer 17

1. Single stranded
2. Contains ribose
3. Can fold up into a greater variety of 3D shapes.
4. Uracil replaces thymine
5. DNA transcription: synthesis of RNA

Question 18

What is the RNA function (3)

Answer 18

1. mRNA: messenger RNA - Contains copies of genetic code from DNA via transcription
2. rRNA: ribosomal RNA - molecule responsible for synthesis of proteins
3. tRNA: transfer RNA - carries code to site of protein synthesis (ribosomes)